PIR only detects motion 5 ft, why?

B

Bama Bob

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The RS 49-425 seems to detect motion out to about 5 feet.  I tested the alarm when I first bought it, it seemed to work to 20' then.  I have taken the PC board out of the case and put it in my case next to the camera. I have glued the lens flat to the case about 1/2 to 3/4 inch from the sensor.  I removed the lens and tested the sensor, again motion was only detected to about 5'.  

Any ideas why I don't get at least 15 to 20 feet?
 

Archilochus

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Hi BB,
I'm guessing that the lens and PIR element are not fitted properly.  Maintaining the proper distance from the lens to the element is important.

Archilochus
 

quackmaster

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1.Do you have glass in front of the PIR lense? that will screw things up.
1.5 Remember the sensor has to warm up for 60 sec with battery attached before you turn it on.
2. Remember its hot down here in the south.  The heat affected my PIR also.  Not that much though. I went ahead and the camera out and it worked fine at night after the air temp had dropped below 85 or so. Took pictures of nothing but racoons though.
3. If you can, tinker with the PIR distance, try something less than 1/2", that might help.
 

Richard Webb

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1/16" on the focal length makes a big difference. 5/8" is a good starting point.
 

wfontjr

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check to see if the fresnel lenses is upside down
 

Possum

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I put my camera in the woods yesterday,  It was 95 degrees in SC yesterday.  In my yard under oak trees in the late evening I get around 25 feet with my RS sensor.  In the woods yesterday I got about 5-10 feet depending  on how fast I moved in front of the camera.  My bet is that its not the sensor but the heat of the day (especially if your sensor is using the same casing that it came in).  My first roll of film only got two daytime pictures out of 16.  They were early in the morning before it was hot.  Test your camera around 11:00pm or early in the morning to see if it is the heat.

I did not read very good-It may be the distance from the lens that is the problem- but do the heat test anyway to make sure. 



(Edited by Possum at 9:43 pm on Aug. 8, 2001)
 
B

Bama Bob

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You're right, I have increased the lens distance a little and now it's about 20 ft again.  Thanks for the help!  :D
 

Gun Docc

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Howdy fellers,

most likely the problem is the summer temps as from what i have noticed with my RS 49-425 cams is that they do not work as good in the heat as say temps in the 50's to 70's.

speaking of measurements from the lens to the sensors , i am a gunsmith and deal with measurements in thousandths of an inch every day so this is simple to me....lol

out of the box these units have the sensor set at .700 thousandths or so from the face of the sensor to the inside face of the lens, which is just a little under 3/4 inch or just a little over 11/16 inch.
i have played with setting the sensor at different distances from the lens and came up with it working the best at around .600 to .625 thousandths from the lens. this seems about the best for the time delay of the pf camera and getting the animal in the center of the pic.

what i have noticed with the setting of the sensor is that if you set it further from the lens, the PIR will have a smaller field of view. and if you set it closer the PIR will have a wider field of view .

so to kinda match the camera's view i set mine up at 5/8 inch from the lens with a 1 inch hole in the box mounted flat on the inside of the unit for it to look out thru.

i have found that some of the RS 49-425 PIR units work best at about .600 and others work best at about .750  . so sometimes you have to play with this lens distance to get all the range you can from them.

out of 7 camera units that i built with the RS 49-425 all of them have a bit different setting of the lens to tune them for better range.

hope this helps,
 

gizz

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Gun Docc - How's the Lamson handling the heat?
 

Gun Docc

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Gizz,

the Lamson is working out to at least 50 feet in this heat when i checked it at about 87 degrees a couple of days ago.

but since you asked it is a smoking here today with the humidity very high too so i will go out and give it another test here in a few minutes ( got one here on the bench to do testing with...hehehe )
will let you know how it does soon afterwards.

Later
 

gizz

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Sounds like a winner! I just purchased 3 pf dates and 3 Lamson(GE's actually) and am getting ready for the big "build". I'm gonna swap out R16 and R17 on the board and use the existing Chip inside the socket without adding a timer. Thing draws about .06 to .07 at idle and should last many months on one 9v. I'm excited and wondered if you have had any strange "events" with the Lamson?
Let me know on the heat test.
Thanks,
gizz
 

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